Structural properties of Mn-substituted hercynite

In this work spinel series with the general formula Fe_1-xMn_xAl₂O₄ (where x = 0, 0.3, 0.5 and 0.7) were synthesized and characterized with respect to their structure and microstructure. X-ray diffractometry (XRD) was used to identify the phase composition that revealed a single phase spinel material. Rietveld refinements of the XRD patterns were carried out in order to determine the lattice and oxygen positional parameters of the spinel compounds. Mössbauer effect measurements were performed at room temperature to determine the local chemical environment of the Fe ions, their valences, and degrees of spinels inversion. It was shown that an increase in the Mn content led to a decrease in the ratio of Fe²⁺ to Fe³⁺. The results obtained from Mössbauer spectroscopy (MS) were used to establish the chemical formulas of the synthesized spinels. Finally, the microstructure that was observed using scanning electron microscopy (SEM) showed a compact microstructure with an octahedral crystal habit.